Marko Ostoja has found hard courts difficult, recording 24–47 across 71 matches (33.8%). The numbers point to a surface that has not consistently suited the game — a key area of opportunity on the calendar.

At Grand Slam level (Australian Open & US Open): Marko Ostoja is 3–4 (42.9%) across 7 Grand Slam matches — below .500, though the elite draw depth at the Slams makes that a notoriously difficult barrier to crack.

2 semifinals on hard without yet reaching a final — consistent deep runs that show the ability to string together wins across a full draw, with the step to the final still to come. 3 quarterfinals adds further depth to that picture.

vs. Top 10 on hard: 1–6 (14.3%, 7 matches). Top 10 opponents have represented a clear ceiling on hard; addressing that deficit is the single biggest lever for improving the overall record here.

By format on hard — best-of-five: 3–4 (42.9%); best-of-three: 21–43 (32.8%). Significantly better in five-set matches — a strong physical profile on hard that tends to tell as matches and tournaments progress.

Best season: 1983 — 4–4 (50.0%) from 8 matches. The best single-season display to date — a useful reference point as the hard record continues to develop.